不同品种和植期甘蔗白叶病自然发病率调查

甘蔗白叶病(sugarcane white leaf, SCWL)是由植原体引起的甘蔗毁灭性病害,对甘蔗生产危害极大。为明确不同品种不同植期SCWL的发病规律,2018年对我国SCWL发病最为严重的耿马芒翁和贺派蔗区进行了SCWL田间发病情况调查和巢式PCR检测分析。田间调查结果表明,不同品种田间自然发病率不同,其中粤糖60号平均发病率最高,为73.50%,柳城05-136平均发病率最低,为13.67%;不同植期田间自然发病率也有差异,新植蔗田间发病率最低,为32.38%,3年宿根蔗的田间发病率最高,为64.33%。病原检测结果表明,所有品种的阳性检出率均在90%以上,其中盈育91-59阳性检出率最低,为90.95%,柳城05-136阳性检出率最高,为96.67%,无白叶症状样品的阳性检出率为81.53%,2年和3年宿根的阳性检出率最高,均为96.67%。本研究结果表明SCWL发病率随宿根年限增加而升高,依据白叶症状进行的田间病害调查不能准确反映SCWL的真实发生情况。

Investigation on natural incidence of sugarcane white leaf in different varieties and crop cycles

Sugarcane white leaf (SCWL) is a devastating disease caused by phytoplasmas, which is extremely harmful to sugarcane production. In order to clarify the occurrence regularity of SCWL in different cultivars and different crop cycles, in 2018, we conducted field investigation and nested PCR detection of SCWL in cane-planting areas of Mangweng and Hepai in Gengma, where SCWL was the most serious in China. The results of field investigation showed that the natural incidence rate of different varieties was different. The average disease incidence rate in Yuetang60 was the highest (73.50%) while Liucheng05-136 had the lowest (13.67%). The na-tural incidence rate in newly planted sugarcane was the lowest (32.38%), whereas, in the three-year ratoon sugarcane it was the highest (64.33%). The results of pathogen detection showed that the positive detection rate in all varieties was above 90%. The positive detection rate of Yingyu91-59 was the lowest (90.95%) and Liucheng05-136 was the highest (96.67%), the positive detection rate of asymptomatic samples was 81.53%, and the two and three-year ratoon sugarcane had the highest positive detection rate (96.67%). The results of this study showed that the incidence of SCWL increased with the increase of crop cycle, and the field investigation based on white leaf symptoms could not accurately reflect the actual occurrence of SCWL.